The only fasting app that reads your Garmin and Apple Watch in real time — and coaches you through every metabolic stage. You don't just see a timer. You see your fast working.
Free to start · Premium unlocks live sync & the AI Coach · No account, ever
Live biometrics
Connect your Garmin or Apple Watch and FastFlow reads your body in real time — so every stage transition reflects what's actually happening inside you, not just a clock.
The metabolic journey
FastFlow maps your fast through six metabolic stages and tells you what's happening in your body — and what to do with each stage. Tap a stage to explore.
Beyond the timer
Every feature is built to make fasting a sustainable habit — informed, calm, and personal.
After each fast, the Coach reviews it against your own baseline — "your HRV held 9ms above your usual" — and tells you what to try next time. Everything runs on your phone. Nothing leaves it.
A guided, step-by-step refeeding flow tuned to your fast length — rehydrate, broth, gentle protein, balanced plate — with a shop for break-fast staples like bone broth and electrolytes.
Streaks, a calendar heatmap of your fasts, and a Morning Reveal that shows your overnight recovery. Consistency over extremes — that's the whole point.
Track your fast from the Lock Screen and Dynamic Island, updated from your watch. Glance, don't obsess.
Tap emoji chips for energy, mood and activity. Count hydration with one tap. Log a whole fast without typing a word.
A native Connect IQ app and watch face keep your fast on your wrist — stage, countdown and biometrics at a glance.
Private by design
FastFlow has no account, no sign-in, and no FastFlow servers holding your data. It's your body — the data stays with you.
Biometrics, fasting history and AI Coach insights are all computed on your phone.
History syncs through your own iCloud account. We have no access to it.
No analytics SDKs, no advertising identifiers, no data sold or shared. Ever.
Pricing
The timer, stages and journaling are free. Premium unlocks the live wearable sync, full AI Coach insights, and your complete fasting history.
Subscriptions are charged to your Apple ID and renew automatically unless turned off at least 24 hours before the end of the period. Manage or cancel anytime in your App Store settings. Terms · Privacy
Get FastFlow
FastFlow for iPhone, with a companion app and watch face for Garmin on the Connect IQ Store.
// Coming soon to both stores